Prelab - Electricity/Magnetism

Please become familiar with the following before entering lab.

Important information:

1. Understand the difference between series and parallel circuits.

2. An ammeter is used to measure current. It is always connected in series with other components in the circuit.

In the diagram at left, the "A" represent the ammeter. It will display the amount of current flowing past that point in the circuit.

3. A voltmeter (galvanometer) is used to measure potential difference in volts. It is always connected across (in parallel with) a component in the circuit to measure the "voltage drop".









Here you can see the measurent of the voltage across the battery and the voltage drop across the bulb.

4. Ohm's law is used to relate voltage, current, and resistance. Please be able to use this.


5. The lead of a pencil is a variable resistor. The amount of resitance it provides is proportional to the length through which current flows. A rheostat is a device that uses variable resistance to control current. You will encounter this in lab.

6. Understand how to read and draw simple circuit diagrams. Please use the other sections of this website to review any of the electricity terminology that is new to you.

7. Magnetism comes from the alignment of electron spins in regions called domains. Every electron propagates a tiny magnetic field. These can add up if the domains are aligned. A large piece of metal in which this has occured is called ferromagnetic. All materials have some kind of interaction when placed in a magnetic field. Click here to see. You will see that even diamagnetic materials like copper can be shown to respond to magnetism.


8. A voltaic cell is shown below. It is a simple battery that converts chemical energy to electrical energy. It consists of an electrolyte (solution containing ions) that allows charges to flow between two metals that have different electric potentials.







We will be using vinegar instead of sulfuric acid to carry the charges from the Zn to the Cu electrodes.

Placing a voltmeter across the two electrodes could yeild up to 1.5 volts.

How long will this voltaic cell last?

More about voltaic cells.